Back pressure

This article covers the technical term. See also: Theater back pressure and back pressure turbine .

In printing technology, the counterpressure is the component of a printing machine that picks up the printing material (e.g. paper) and carries the so-called elevator . The counter pressure is either a cylinder ( pressure cylinder ) or a flat plate (crucible). It can be moveable, rigidly mounted or designed as a gripper carrier.

The counter pressure is usually made of solid iron, as it has to be very torsion-resistant and resistant to impressions. Cast iron is preferred because it has shock-absorbing properties.

The counterpressure is designed in such a way that an elevator with a thickness of 1 to 2 mm can be installed in the so-called recess . Depending on the type of machine and type of print job, the elevator consists of several layers (of different hardness) of paper , cellulose film and / or rubber blankets. When punching, a punched sheet is pulled onto the counter pressure. He carries the die when embossing . Elevator and counterpressure form a unit, which in turn is only called counterpressure.

In offset printing machines , no counter pressure, but plate adjustments are made. This is also incorrectly referred to as the elevator, although this is not required on the counter pressure and instead sits behind the mold (either behind the plate or behind the rubber blanket). It only serves to compensate for Schmitz , but not for force adjustment and elastic pressure compensation as in letterpress printing .